An example of a conventional cutting insert is referred to as a negative type cutting insert, as disclosed in Patent Document 1. The cutting insert disclosed in Patent Document 1 includes two end surfaces which are opposed to each other, a peripheral side surface which connects the two end surfaces, and cutting edges which are arranged in an intersecting edge between each of the end surfaces and the peripheral side surface. The peripheral side surface extends in a direction perpendicular to each end surface. In a negative type cutting insert, the arrangement of cutting edges in two end surfaces thereof results in a large number of usable cutting edges, which is economical.